Abstract:

Disclosed herein is a mask to be worn by a subject on its face for use in
respiratory monitoring and/or diagnostics. In general, the mask comprises
at least one transducer responsive to sound and airflow for generating a
data signal representative thereof, and a support structure shaped and
configured to rest on the subject's face and thereby delineate a nose and
mouth area thereof. The support structure comprises two or more outwardly
projecting limbs that, upon positioning the mask, converge into a
transducer supporting portion for supporting the at least one transducer
at a distance from the area, thereby allowing for monitoring via the at
least one transducer of both sound and airflow produced by the subject
while breathing. The limbs may, in some examples, have along at least a
portion thereof, an inward-facing channel defined therein for channeling
toward a given transducer, air flow produced by the subject while
breathing. A method is also disclosed for remotely diagnosing a breathing
disorder of a subject.

Claims:

1. A mask to be worn by a subject on its face for use in respiratory
monitoring, the mask comprising: at least one transducer responsive to
sound and airflow for generating a data signal representative thereof;
and a support structure shaped and configured to rest on the subject's
face and thereby delineate a nose and mouth area thereof, and comprising
two or more outwardly projecting limbs that, upon positioning the mask,
converge into a transducer supporting portion for supporting said at
least one transducer at a distance from said area, thereby allowing for
monitoring via said at least one transducer of both sound and airflow
produced by the subject while breathing.

2. The diagnostic mask of claim 1, further comprising a restraining
mechanism coupled to said structure for restraining the mask in position
on the subject's face during use.

3. The diagnostic mask of claim 1, each of said two or more outwardly
projecting limbs having, along at least a portion thereof, an
inward-facing channel defined therein for channeling at least a portion
of said airflow toward said at least one transducer.

4. The diagnostic mask of claim 1, wherein said two or more outwardly
projecting limbs comprise two opposed side limbs and a central limb
converging into said transducer supporting portion to form a tripod-like
structure extending from said area when the mask is in position.

5. The diagnostic mask of claim 1, said transducer supporting portion
having a funneling shape oriented so to funnel at least a portion of said
airflow toward said at least one transducer.

6. The diagnostic mask of claim 5, wherein said funneling shape fluidly
extends into an inward-facing channel defined along at least a portion of
each of said two or more outwardly projecting limbs, whereby said at
least portion of said airflow is channeled thereby toward said at least
one transducer.

7. The mask of claim 1, consisting of a self-contained mask, further
comprising a recording device mounted to said support structure and
operatively coupled to said at least one transducer for recording said
sound and airflow in operation, wherein said recording device is further
configured for transferring said recording for processing by a remote
respiratory disorder diagnostic system.

9. The mask of claim 7, said support structure comprising a frontal
member for resting same above the bridge of the subject's nose, wherein
said recording device is disposed on said frontal member thereby reducing
an obtrusiveness thereof.

10. The mask of claim 7, wherein said recording device comprises one or
more of a removable data storage medium, a wireless communication device
and a wired communication port for digitally transferring said recording.

11. The mask of claim 1, said support structure further comprising a
face-framing portion from which said two or more limbs extend, said
face-framing portion further delineating said area by at least partially
circumscribing same, wherein said face-framing portion is shaped to
substantially contour the subject's face when in position thereby
facilitating proper positioning of the mask.

12. The mask of claim 1, wherein said two or more limbs provide for
minimal airflow resistance resulting in substantially reduced dead space.

13. The mask of claim 1, said at least one transducer comprising a first
transducer predominantly responsive to airflow and a second transducer
predominantly responsive to sound.

14. The mask of claim 13, wherein said first transducer is selected from
the group consisting of a microphone, an air flow sensor and a pressure
sensor, and wherein said second transducer is a microphone.

15. The mask of claim 1, said at least one transducer comprising a first
microphone operable to record both sound and airflow, the mask further
comprising a second microphone disposed and configured to predominantly
record sound, such that data collected via said second microphone can be
used to filter data collected via said first microphone.

16. The mask of claim 1, wherein sound and airflow recorded via said mask
is suitable for breathing disorder diagnostics.

17. A mask to be worn by a subject on its face for use in respiratory
monitoring, the mask comprising: a transducer responsive to airflow for
generating a data signal representative thereof; and a support structure
shaped and configured to rest on the subject's face and thereby delineate
a nose and mouth area thereof, and comprising two or more outwardly
projecting limbs that, upon positioning the mask, converge into a
transducer supporting portion for supporting said transducer at a
distance above said area, each of said two or more outwardly projecting
limbs having, along at least a portion thereof, an inward-facing channel
defined therein for channeling toward said transducer, air flow produced
by the subject while breathing, thereby allowing for monitoring of said
airflow.

18. The mask of claim 17, wherein said two or more outwardly projecting
limbs comprise two opposed lower side limbs and a central upper limb
converging into said transducer supporting portion to form a tripod-like
structure above said area when the mask is in position.

19. The mask of claim 17, said transducer supporting portion having a
funneling shape fluidly extending from each said inward-facing channel to
further funnel channeled air flow toward said transducer.

20. The mask of claim 17, wherein said transducer is selected from the
group consisting of a microphone, a pressure sensor and an airflow
sensor.

21. The mask of claim 17, further comprising a microphone disposed and
configured to be predominantly responsive to sound produced by the
subject while breathing.

22. The mask of claim 21, wherein said microphone is disposed on the mask
at a distance from said transducer to reduce exposure to airflow produced
by the subject while breathing.

23. A method for remotely diagnosing a breathing disorder of a subject,
the method comprising the steps of: providing the subject access to a
self-contained diagnostic mask to be worn on the subject's face while
breathing, said mask comprising at least one transducer responsive to
sound and airflow for generating a signal representative thereof, and a
recording device operatively coupled thereto; recording on said recording
device sound and airflow signals produced by the subject while breathing;
transferring said recorded signals to a remotely located diagnostic
center for processing; and diagnosing the breathing disorder solely on
the basis of said processed sound and airflow signals.

24. The method of claim 23, wherein said recording step comprises storing
said sound and airflow signals on a removable data storage device, and
wherein said transferring step comprises delivering said removable data
storage to said diagnostic center.

25. The method of claim 23, wherein said transferring step comprises
uploading said recorded signals to a local computing device and
communicating said uploaded signals to a remotely located diagnostic
center device.

Description:

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of copending
international application no. PCT/CA2009/001644, filed Nov. 16, 2009,
entitled "METHOD AND APPARATUS FOR MONITORING BREATHING CYCLE BY
FREQUENCY ANALYSIS OF AN ACOUSTIC DATA STREAM", which claims priority
under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No.
61/193,320, filed Nov. 17, 2008, entitled "TRACKING PHASES OF THE
BREATHING CYCLE BY FREQUENCY ANALYSIS OF ACOUSTIC DATA." The present
application further claims priority under 35 U.S.C. §119(e) to U.S.
Provisional Patent Application No. 61/272,460, filed Sep. 25, 2009,
entitled "APPARATUS AND METHOD FOR USE IN THE DIAGNOSES OF OBSTRUCTIVE
SLEEP BREATHING DISORDERS USING DIGITIZED ACOUSTIC DATA." The disclosures
set forth in the referenced applications are incorporated herein by
reference in their entireties, including all information as originally
submitted to the United States Patent and Trademark Office.

FIELD OF THE DISCLOSURE

[0002] The present disclosure relates to respiratory diagnostic and
monitoring systems, and in particular, to a mask and method for use in
respiratory monitoring and diagnostics.

BACKGROUND

[0003] Several clinical conditions require close monitoring of respiratory
activity including respiratory failure, respiratory tract infections as
well as respiratory depression associated with anesthesia and sedatives.
Also, respiratory disorders are known to disturb sleep patterns. For
example, recurrent apneas and hypopnea lead to intermittent hypoxia that
provokes arousals and fragmentation of sleep, which in turn may lead to
restless sleep, and excessive daytime sleepiness. Repetitive apneas and
intermittent hypoxia may also elicit sympathetic nervous system
activation, oxidative stress and elaboration of inflammatory mediators
which may cause repetitive surges in blood pressure at night and increase
the risk of developing daytime hypertension, atherosclerosis, heart
failure, and stroke independently from other risks.

[0004] There remains a need for improved tools and methods for monitoring
respiratory activity, for example in a clinical setting, or again in
diagnosing and/or monitoring respiratory disorders, as discussed above,
in order to reduce or even obviate the risks that may be associated
therewith.

[0005] Namely, while some have proposed diagnostic tools and methods for
diagnosing, monitoring and/or generally investigating certain breathing
disorders, these tools and methods are often particularly invasive and/or
uncomfortable for the subject at hand, and therefore, can yield
unsatisfactory results. For instance, many diagnostic procedures are
solely implemented within a clinical environment, which amongst other
deficiencies, do not allow for monitoring a subject in its natural
environment, leading to skewed or inaccurate results, or in the least,
forcing the subject through an unpleasant and mostly uncomfortable
experience.

[0006] Alternatively, different portable devices have been suggested for
the diagnosis of sleep apneas; however, these solutions generally require
the subject to position and attach several wired electrodes themselves in
the absence of a health care provider. Unfortunately, subject-driven
electrode positioning and installation often leads to a reduction in
subject comfort and compliance, and increases the chance that the
electrodes will be detached or displaced in use. Since accurate
positioning and installation of such electrodes are paramount to proper
diagnostics, captured signals in such situations are often unreliable, a
measure which can only effectively be determined once the data is
transferred back to a health center, at which point, such data, if
properly identified, must be withdrawn from the study. Furthermore, such
devices regularly need to be shipped back to the health center for
processing and, given their generally invasive nature, for hygienic
reconditioning, e.g. disinfection.

[0007] Similarly, in a clinical setting, while the positioning and
attachment of monitoring electrodes may be completed by an experienced
health care professional, the devices currently used in such settings
generally at best leave the subject physically wired to one or more
monitoring devices, if not via more invasive techniques, which wiring can
be a particular nuisance to the subjects general comfort and mobility,
and obtrusive to individuals or health care practitioners maneuvering
around the subject. For example, International Application Publication
No. WO 01/15602 describes a clinical system wherein a microphone is
suspended from the ceiling above the subject, the recorded data of which
is combined with readings from an esophageal pressure catheter and nasal
airflow monitoring.

[0008] Less intrusive methods have been proposed, for example in U.S. Pat.
No. 5,797,852, wherein a microphone is suspended from a base device
sitting on the headboard of the subject's bed to record sound produced by
the subject's breathing, which base device further comprises a second
microphone to record ambient noise in the subject's room. Clearly, the
accuracy of the recordings is highly dependent on the subject's position,
which will most likely vary during a given sleeping period. Other
examples found in U.S. Pat. No. 6,142,950 and US Patent Application
Publication No. 2002/0123699 provide facially mounted devices configured
for either airflow or sound recordal, respectively. While these latter
devices may be less dependent on subject positioning, they are equally
limited in the type of data acquired for processing, as only one of
airflow or sound can be accessed by any one of these designs. Similarly,
International Application Publication No. WO 2006/008745 describes the
use of a standard headset having a microphone disposed in front of the
subject's mouth to monitor expiratory airflow, with other subject driven
and ambient sounds being expressly filtered out as parasitical to the
intended system. Furthermore, each of the above examples proposes a
configurationally limited design that generally suffers from various
deficiencies which, in operation, limit its effectiveness in capturing
accurate and usable data.

[0009] Accordingly, there is a need for a new mask and method for use in
respiratory monitoring and/or diagnostics that overcome some of the
drawbacks of known techniques, or at least, that provide the public with
a useful alternative. Furthermore, improvements and/or alternative
approaches in the type and quality of information collected in monitoring
and/or diagnosing a subject, as well as in the methods and procedures
implemented in processing and analyzing this information are needed to
yield better results without, for example, necessarily requiring further
data diversity which, ultimately, can result in greater constraints to
the subject's mobility and/or comfort.

[0010] This background information is provided to reveal information
believed by the applicant to be of possible relevance to the present
invention. No admission is necessarily intended, nor should be construed,
that any of the preceding information constitutes prior art against the
present invention.

SUMMARY OF THE GENERAL INVENTIVE CONCEPT

[0011] An object of the invention is to provide a mask and method for use
in diagnosing breathing disorders. In accordance with an aspect of the
invention, there is provided a mask to be worn by a subject on its face
for use in respiratory monitoring, the mask comprising: at least one
transducer responsive to sound and airflow for generating a data signal
representative thereof; and a support structure shaped and configured to
rest on the subject's face and thereby delineate a nose and mouth area
thereof; and comprising two or more outwardly projecting limbs that, upon
positioning the mask, converge into a transducer supporting portion for
supporting said at least one transducer at a distance from said area,
thereby allowing for monitoring via said at least one transducer of both
sound and airflow produced by the subject while breathing.

[0012] In accordance with another embodiment of the invention, there is
provided a mask to be worn by a subject on its face for use in
respiratory monitoring, the mask comprising: a transducer responsive to
airflow for generating a data signal representative thereof; and a
support structure shaped and configured to rest on the subject's face and
thereby delineate a nose and mouth area thereof, and comprising two or
more outwardly projecting limbs that, upon positioning the mask, converge
into a transducer supporting portion for supporting said transducer at a
distance above said area, each of said two or more outwardly projecting
limbs having, along at least a portion thereof; an inward-facing channel
defined therein for channeling toward said transducer, air flow produced
by the subject while breathing, thereby allowing for monitoring of said
airflow.

[0013] In accordance with another embodiment of the invention, there is
provided a method for remotely diagnosing a breathing disorder of a
subject, the method comprising the steps of: providing the subject access
to a self-contained diagnostic mask to be worn on the subject's face
while breathing, said mask comprising at least one transducer responsive
to sound and airflow for generating a signal representative thereof, and
a recording device operatively coupled thereto; recording on said
recording device sound and airflow signals produced by the subject while
breathing; transferring said recorded signals to a remotely located
diagnostic center for processing; and diagnosing the breathing disorder
solely on the basis of said processed sound and airflow signals.

[0014] In an exemplary embodiment, there is provided a method for
processing acoustic signal data for use in monitoring the breathing cycle
of an individual. The method comprises collecting and generating a data
set representative of an acoustic data stream plot of wave amplitude
versus time, the data set originating from breathing sounds of an
individual and segmenting the acoustic data stream plot into segments
wherein each segment spans a predetermined time period. The acoustic data
is transformed so as to produce a frequency spectrum in each segment and
the frequency spectrum in each segment is transformed so as to produce a
plurality of magnitude bins. A sample including a plurality of segments
is identified and a sum of lower frequency magnitude bins within a
predetermined lower frequency range and a sum of higher frequency
magnitude bins within a predetermined higher frequency range are
determined. The sum of higher frequency magnitude bins in the sampling is
divided by the sum of lower frequency magnitude bins so as to produce a
mean bands ratio. A sum of lower frequency magnitude bins and a sum of
higher frequency magnitude bins within a given segment is determined and
the sum of higher frequency magnitude bins is divided by the sum of lower
frequency magnitude bins within said given segment so as to produce a
first bands ratio and it is determined whether said first bands ratio is
greater or less than said mean bands ratio by at least a predetermined
multiplier so as to provide an indication of said breathing cycle.

[0015] In some exemplary embodiments, the predetermined multiplier is at
least 1. In other exemplary embodiments, the predetermined multiplier is
greater than 1.5. In still other exemplary embodiments, the predetermined
multiplier is greater than 2.

[0016] In some exemplary embodiments, the first bands ratio is labeled as
inspiration if the first bands ratio is greater than the mean bands ratio
by at least the predetermined multiplier.

[0017] In some exemplary embodiments, the first bands ratio is labeled as
expiration if the first bands ratio is less than the mean bands ratio by
at least the predetermined multiplier.

[0018] In some exemplary embodiments, the breathing sounds are collected
for a period of time of from about 10 seconds to about 8 hours. In some
exemplary embodiments, the breathing sounds are collected for a period of
time of from about 10 seconds to about 20 minutes. In some exemplary
embodiments, the breathing sounds are collected for a period of time of
from about 10 seconds to about 25 seconds. In some exemplary embodiments,
the breathing sounds are collected for a period of time of greater than
20 minutes. In some exemplary embodiments, the breathing sounds are
collected for a period of time about 25 seconds.

[0019] In some exemplary embodiments, each of the segments represents a
time period of from about 50 ms to about 1 second. In some exemplary
embodiments, each of the segments represents a time period of from about
100 ms to about 500 ms. In some exemplary embodiments, each of the
segments represents a time period of about 200 ms.

[0020] In some exemplary embodiments, the lower frequency range is from
about 0 Hz to about 500 Hz. In some exemplary embodiments, the lower
frequency range is from about 10 Hz to about 400 Hz.

[0021] In some exemplary embodiments, the higher frequency range is from
about 500 Hz to about 25,000 Hz. In some exemplary embodiments, the
higher frequency range is from about 400 Hz to about 1,000 Hz.

[0022] In some exemplary embodiments, the sampling of the plurality of
segments is selected from the recording randomly. In other exemplary
embodiments, the sampling of the plurality of segments includes
substantially all of the segments in the recording. In still other
exemplary embodiments, the mean bands ratio is determined from at least
two segments preceding the first bands ratio segment.

[0023] In some exemplary embodiments, the method further comprises, before
the generating step, recording the breathing sounds with at least one
microphone.

[0024] In some exemplary embodiments, the audio collecting of breathing
sounds of an individual comprises airflow sounds resultant from the
individual's breathing applying air pressure to a diaphragm of the
microphone. In some exemplary embodiments, the collecting of breathing
sounds of an individual comprises breathing sounds resultant from the
breathing of the individual being recorded by the microphone. In some
exemplary embodiments, the collecting of breathing sounds of an
individual comprises airflow sounds resultant from the individual's
breathing applying air pressure to a diaphragm of the microphone and
actual breathing sounds resultant from the individual being recorded by
the microphone.

[0025] In some exemplary embodiments, the collection of breathing sounds
is digitized in real-time. In some exemplary embodiments, the processing
of the collected waveform data is performed in real-time.

[0026] In some exemplary embodiments, breathing sounds are collected by at
least a first microphone and a second microphone. The first microphone is
operable to collect breathing sounds and airflow sounds resultant from
the individual's breathing applying air pressure to a diaphragm of the
first microphone and the second microphone is operable to collect
breathing sounds of the individual. In some exemplary embodiments, the
method further comprises, before the generating step, filtering acoustic
data of an output representative of second microphone from the acoustic
signal data representative of an output of the first microphone so as to
provide an acoustic data stream of an audio recording of substantially
airflow sounds of the individual.

[0027] In some exemplary embodiments, the at least one microphone is
provided in a structure including one or more openings of sufficient size
to minimize airflow resistance and be substantially devoid of dead space.

[0028] In another exemplary embodiment, there is provided an apparatus for
transforming acoustic signal data breathing sounds into a graphical
representation indicative of breathing cycle phases including inspiration
phases and expiration phases. The apparatus comprises at least one
microphone for collecting acoustic signal data resultant from the
breathing of an individual during a given time period and an acoustic
signal data digitizing module for digitizing the acoustic signal data to
produce an acoustic data stream plot representative of wave amplitude
versus time. At least one processor operable for receiving the acoustic
data stream plot is provided. The processor is configured for segmenting
the acoustic data stream plot into a plurality of segments of a
predetermined length of time, transforming the acoustic data stream in
each of the plurality of segments so as to produce a plurality of
frequency spectra wherein each frequency spectrum is representative of
one of the plurality of segments, transforming each frequency spectrum so
as to produce a plurality of magnitude bins in each segment, determining
a sum of lower frequency magnitude bins within a predetermined lower
frequency range and a sum of higher frequency magnitude bins within a
predetermined higher frequency range within a sampling of the plurality
segments, dividing the sum of higher frequency magnitude bins by the sum
of lower frequency magnitude bins in the sampling so as to produce a mean
bands ratio, determining a sum of lower frequency magnitude bins and a
sum of higher frequency magnitude bins within a given segment, dividing
the sum of higher frequency magnitude bins by the sum of lower frequency
magnitude bins within said given segment so as to produce a first bands
ratio, comparing said mean bands ratio to said first bands ratio and
determining whether said first bands ratio is greater or less than said
mean bands ratio by at least a predetermined multiplier so as to
determine if said given segment is an inspiration phase or an expiration
phase of the breathing cycle. An information relay module in
communication with the at least one processor for providing the
transformed data to an operator as first indicia representing inspiration
and expiration is also provided.

[0029] In some exemplary embodiments, the apparatus further comprises a
sensor for sensing respiratory movements of an abdomen or rib region of
the individual and generating a signal indicative thereof. The processor
is operative to receive the signal and to identify respiratory expansion
during inspiration and respiratory contraction during expiration. The
information relay is operable to provide data to an operator generated as
second indicia representing the respiratory movements.

[0030] In some exemplary embodiments, the information relay module is
provided as a display module for displaying the transformed data as a
processed wave amplitude versus time plot. The inspiration phases are
identifiable by rising regions of said processed wave amplitude versus
time plot and the expiration phases are identifiable by falling regions
of said processed wave amplitude versus time plot. In some exemplary
embodiments, the information relay module is operable so as to provide an
operator audio cues representing the inspiration and expiration phases of
an individual's breathing. In some exemplary embodiments, the information
relay module is provided as a display module operable for displaying
visual cues representing the inspiration and expiration phases of an
individual's breathing. In some exemplary embodiments, the information
relay module is operable so as to provide an operator printed visual
indicia representing the inspiration and expiration phases of an
individual's breathing.

[0031] In some exemplary embodiments, the breathing sounds are collected
by at least a first microphone and a second microphone. The first
microphone is operable to collect acoustic signal data breathing sounds
and airflow sounds resultant from the individual's breathing applying air
pressure to a diaphragm of the first microphone and the second microphone
is operable to collect acoustic signal data breathing sounds of the
individual. In some exemplary embodiments, the acoustic signal data
collected by the second microphone are subtracted from the acoustic
signal data collected by the first microphone so as to provide an
acoustic signal data recording of substantially airflow sounds of the
individual.

[0032] In some exemplary embodiments the at least one microphone is
provided in a structure including one or more openings sufficient to
reduce airflow resistance and be substantially devoid of dead space.

[0033] In another exemplary embodiment, there is provided an apparatus for
transforming acoustic signal data breathing sounds into a graphical
representation indicative of breathing cycle phases including inspiration
phases and expiration phases. The apparatus comprises at least one
microphone for collecting acoustic signal data resultant from the
breathing of an individual during a given time period and an acoustic
signal data digitizing module for receiving and digitizing sounds via a
transducing link from the at least one microphone. The audio signal
digitizing module is operable to produce an acoustic data stream plot
representative of wave amplitude versus time. A module for segmenting a
plurality of adjacent audio samples from the acoustic data stream plot
into a plurality of segments of a predetermined length of time is
provided. A module for transforming the acoustic data stream in each of
the plurality of segment so as to produce a plurality of frequency
spectra wherein each frequency spectrum is representative of one of the
plurality of segments is provided. A module for transforming each
frequency spectrum so as to produce a plurality of magnitude bins in each
segment is provided. A module for determining a sum of lower frequency
magnitude bins within a predetermined lower frequency range and a sum of
higher frequency magnitude bins within a predetermined higher frequency
range within a sampling of the plurality segments is provided. A module
for dividing the sum of higher frequency magnitude bins by the sum of
lower frequency magnitude bins in the sampling of the plurality of
segments so as to produce a mean bands ratio is provided. A module for
determining a sum of lower frequency magnitude bins and a sum of higher
frequency magnitude bins within a given segment is provided. A module for
dividing the sum of higher frequency magnitude bins by the sum of lower
frequency magnitude within said given segment so as to produce a first
bands ratio is provided. A module for comparing said mean bands ratio to
said first bands ratio and determining whether said first bands ratio is
greater or less than said mean bands ratio by at least a predetermined
multiplier so as to determine if said given segment is an inspiration
phase or an expiration phase of the breathing cycle is provided. An
information rely module in communication with the module for comparing
said mean bands ratio to said first bands ratio for providing the
transformed data to an operator as indicia representing inspiration and
expiration.

[0034] In yet another exemplary embodiment, there is provided a computer
implemented apparatus for transforming acoustic signal data breathing
sounds into a graphical representation indicative of breathing cycle
phases including inspiration phases and expiration phases. The apparatus
comprises at least one microphone for collecting acoustic signal data
breathing sounds resultant from the breathing of an individual during a
given time period and an acoustic signal data digitizing module for
receiving and digitizing sounds via a transducing link from the at least
one microphone. The audio signal digitizing module is operable to produce
an acoustic data stream plot representative of a wave amplitude versus
time. At least one processor operable for receiving the acoustic data
stream plot is provided. The processor is configured for segmenting a
plurality of adjacent audio samples from the acoustic data stream plot
into a plurality of segments of a predetermined length of time,
transforming the acoustic data stream in each of the plurality of
segments so as to produce a plurality of frequency spectra wherein each
frequency spectrum is representative of one of the plurality of segments,
transforming each frequency spectrum so as to produce a plurality of
magnitude bins in each segment, determining a sum of lower frequency
magnitude bins within a predetermined lower frequency range and a sum of
higher frequency magnitude bins within a predetermined higher frequency
range within a sampling of the plurality segments, dividing the sum of
higher frequency magnitude bins by the sum of lower frequency magnitude
bins in the sampling of the plurality of segments so as to produce a mean
bands ratio, determining a sum of lower frequency magnitude bins and a
sum of higher frequency magnitude bins within a given segment, dividing
the sum of higher frequency magnitude bins by the sum of lower frequency
magnitude bins within said given segment so as to produce a first bands
ratio, comparing said mean bands ratio to said first bands ratio and
determining whether said first bands ratio is greater or less than said
mean bands ratio by at least a predetermined multiplier so as to
determine if said given segment is an inspiration phase or an expiration
phase of the breathing cycle. An information rely module in communication
with the at least one processor for providing the transformed data to an
operator as indicia representing inspiration and expiration is also
provided.

[0035] In still another exemplary embodiment, there is provided a method
for processing acoustic signal data for use in monitoring a breathing
cycle of an individual. The method comprises generating a data set
representative of an acoustic data stream plot of wave amplitude versus
time. The data set originating from breathing sounds of an individual.
The acoustic data stream plot is transformed to yield at least one
relatively higher frequency spectral characteristic and at least one
relatively lower frequency spectral characteristic. A proportional value
of the relatively higher frequency spectral characteristics to the
relatively lower frequency spectral characteristics is determined, and
least first output indicative of an inspirational breathing phase
according to a first range of the proportional value and/or at least one
second output indicative of an expirational breathing phase according to
a second range of the second proportional value is generated.

[0036] In yet another exemplary embodiment, there is provided a device for
processing acoustic signal data for use in monitoring a breathing cycle
of an individual. The device comprises a means for generating a data set
representative of an acoustic data stream plot of wave amplitude versus
time. The data set originating from breathing sounds of an individual.
Means for transforming the acoustic data stream plot to yield at least
one relatively higher frequency spectral characteristic and at least one
relatively lower frequency spectral characteristic is provided. Means for
determining a proportional value of the relatively higher frequency
spectral characteristic to the relatively lower frequency spectral
characteristic is provided and means for generating at least first output
indicative of an inspirational breathing phase according to a first range
of the proportional value and/or at least one second output indicative of
an expirational breathing phase according to a second range of the second
proportional value is provided.

[0037] In still another exemplary embodiment, there is provided a method
for processing acoustic signal data for use in monitoring inspirational
and expirational phases of a breathing cycle of an individual. The method
comprises generating a data set representative of an acoustic data stream
plot of wave amplitude versus time. The data set originating from
breathing sounds of an individual. The acoustic data stream plot is
transformed to yield inspirational spectral data for at least one
inspirational phase and expirational spectral data for at least one
expirational phase and the shape of the inspirational and expirational
frequency spectra for tracking breathing activities is characterized to
identify inspirational and expirational breathing phases in subsequent
breathing cycles.

[0038] In another exemplary embodiment, there is provided a device for
processing acoustic signal data for use in monitoring inspirational and
expirational phases of a breathing cycle of an individual. The device
comprises means for generating a data set representative of an acoustic
data stream plot of wave amplitude versus time. The data set originating
from breathing sounds of an individual. Means for transforming the
acoustic data stream plot to yield inspirational spectral data for at
least one inspirational phase and expirational spectral data for at least
one expirational phase as provided and means for characterizing the shape
of the inspirational and expirational frequency spectra for tracking
breathing activities to identify inspirational and expirational breathing
phases in subsequent breathing cycles is also provided.

[0039] Other aims, objects, advantages and features of the invention will
become more apparent upon reading of the following non-restrictive
description of specific embodiments thereof, given by way of example only
with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

[0040] Several embodiments of the present disclosure will be provided, by
way of examples only, with reference to the appended drawings, wherein:

[0041] FIG. 1 is a plot of an exemplary microphone response curve of an
exemplary embodiment;

[0042] FIG. 2a is side view of an exemplary embodiment of a microphone and
transducer set-up on an individual wherein the microphone is attached to
a face mask located on the front of an individual's face;

[0043] FIG. 2b is side view of an exemplary embodiment of a 2-microphone
and transducer set-up on an individual wherein the microphones are
attached to a face mask located on the front of an individual's face;

[0044] FIG. 3 is a schematic computer system in accordance with an
apparatus for transforming breathing sounds in inspiration and expiration
phases;

[0045] FIG. 4 is a block diagram of a computer system in accordance with
the apparatus of FIG. 3;

[0047] FIG. 6a is an exemplary set-up of Respiratory Inductance
Plethysmography (RIP) on an individual and the microphone and transducer
equipment of FIGS. 2a and 2b;

[0048] FIG. 6b is an exemplary plot of 25-second long recording of
breathing sounds and simultaneous RIP signals from a representative
individual wherein the dashed line indicates the separation of
inspiration and expiration cycles;

[0049] FIG. 7a is a representative digitized raw data breathing sound
amplitude versus time plot of a single breathing cycle with the three
phases of respiration;

[0050] FIG. 7b is a representative frequency spectrum of the inspiration
phase of FIG. 7a;

[0051] FIG. 7c is a representative frequency spectrum of the expiration
phase of FIG. 7a;

[0052] FIG. 8a is a representative plot of the average frequency magnitude
spectrum and standard deviations of breathing sounds for inspiration in
an individual;

[0053] FIG. 8b is a representative plot of the average frequency magnitude
spectrum and standard deviations of breathing sounds for expiration in an
individual;

[0054] FIG. 9 is a flow diagram of the method for monitoring, identifying
and determining the breathing phases from breathing sound data;

[0056] FIG. 10b is a comparative plot of the RIP data of FIG. 10a and the
breathing phases found using the method of FIG. 9 for monitoring,
identifying and determining breathing phases wherein the positive values
of the dashed line represent inspiration and the negative values of the
dashed line represent expiration;

[0057] FIG. 11 is a perspective view of a mask for use in respiratory
monitoring and/or diagnostics, in accordance with one embodiment of the
invention;

[0058] FIG. 12 is a side view of the mask of FIG. 12 when positioned on a
subject's face, in accordance with one embodiment of the invention;

[0059] FIG. 13 is a front perspective view of an outwardly projecting
portion of a respiratory monitoring and/or diagnostic mask, for example
as shown in FIG. 11, showing in stippled lines limb extremities and
reinforcements, and a transducer supporting extension thereof;

[0060] FIG. 14 is a rear perspective view of the outwardly projecting
portion of FIG. 13;

[0061] FIG. 15 is a top plan view of the outwardly projecting portion of
FIG. 13;

[0062] FIG. 16 is a rear view of the outwardly projecting portion of FIG.
13;

[0063] FIG. 17 is a front view of the outwardly projecting portion of FIG.
13;

[0064] FIG. 18 is a bottom plan view of the outwardly projecting portion
of FIG. 13;

[0065] FIG. 19 is a left side view of the outwardly projecting portion of
FIG. 13;

[0066] FIG. 20 is a right side view of the outwardly projecting portion of
FIG. 13;

[0067] FIG. 21 is a right side view of the outwardly projecting portion of
FIG. 13, showing in stippled lines coupling of same to a face resting
portion and restraining mechanism of the mask when positioned on the face
of a subject, as well as a microphone mounted within a transducer
supporting portion of the outwardly projecting portion for capturing
sound and airflow produced by the subject while breathing;

[0068] FIG. 22 is a cross section of the outwardly projecting portion of
FIG. 13, showing in stippled lines positioning of same on the face of a
subject;

[0069] FIG. 23 is a schematic diagram of a process for decoupling a data
stream representative of airflow from a combined data stream
representative of both airflow and sound, in accordance with one
embodiment of the invention; and

[0070] FIG. 24 is a schematic diagram comparing a standard respiratory
diagnosis approach with a respiratory diagnostic method in accordance
with one embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0071] It should be understood that the disclosure is not limited in its
application to the details of construction and the arrangement of
components set forth in the following description or illustrated in the
drawings. The disclosure is capable of other embodiments and of being
practiced or of being carried out in various ways. Also, it is to be
understood that the phraseology and terminology used herein is for the
purpose of description and should not be regarded as limiting. The use of
"including," "comprising," or "having" and variations thereof herein is
meant to encompass the items listed thereafter and equivalents thereof as
well as additional items. Unless limited otherwise, the terms
"connected," "coupled," and "mounted," and variations thereof herein are
used broadly and encompass direct and indirect connections, couplings,
and mountings. In addition, the terms "connected" and "coupled" and
variations thereof are not restricted to physical or mechanical or
electrical connections or couplings. Furthermore, and as described in
subsequent paragraphs, the specific mechanical or electrical
configurations illustrated in the drawings are intended to exemplify
embodiments of the disclosure. However, other alternative mechanical or
electrical configurations are possible which are considered to be within
the teachings of the instant disclosure. Furthermore, unless otherwise
indicated, the term "or" is to be considered inclusive.

[0072] With reference to the disclosure herein and the appended figures, a
mask and method for use in respiratory monitoring and diagnostics is
henceforth described, as well as a method for monitoring, identifying
and/or determining characteristics of an individual's breathing,
including breathing phases thereof, using a processed acoustic signal
data stream collected and/or recorded waveform data. In one example, the
waveform data is collected from or is associated with breathing sounds
and other sounds from one or more microphones or other sound wave
collecting equivalents thereof.

[0073] In some embodiments, various systems and methods, or subsystems and
procedures, may involve the use of a control unit or other such computing
device, in which some or all of its associated components are computer
implemented that may be provided in a number of forms. They may be
embodied in a software program configured to run on one or more general
purpose computers, such as a personal computer, or on a single custom
built computer, such as a programmed logic controller (PLC) which is
dedicated to the function of the system alone. The system may,
alternatively, be executed on a more substantial computer mainframe. The
general purpose computer may work within a network involving several
general purpose computers, for example those sold under the trade names
APPLE or IBM, or clones thereof, which are programmed with operating
systems known by the trade names WINDOWS®, LINUX®, MAC O/S® or
other well known or lesser known equivalents of these. The system may
involve pre-programmed software using a number of possible languages or a
custom designed version of a programming software sold under the trade
name ACCESS or other programming software. The computer network may be a
wired local area network, or a wide area network such as the Internet, or
a combination of the two, with or without added security, authentication
protocols, or under "peer-to-peer" or "client-server" or other networking
architectures. The network may also be a wireless network or a
combination of wired and wireless networks. The wireless network may
operate under frequencies such as those dubbed `radio frequency` or "RF"
using protocols such as the 802.11, TCP/IP, BLUE TOOTH and the like, or
other well known Internet, wireless, satellite or cell packet protocols.
Also, the present method may also be implemented using a
microprocessor-based, battery powered device.

[0074] FIG. 3 shows a general computer system on which embodiments may be
practiced. The general computer system comprises information relay module
(1.1). In some embodiments, the information relay module (1.1) comprises
a means for providing audible cues, such as speakers. In some
embodiments, the information relay module is comprised of a display
device or module (1.1) with a display screen (1.2). Examples of display
device are Cathode Ray Tube (CRT) devices, Liquid Crystal Display (LCD)
Devices etc. The general computer system can also have other additional
output devices like a printer. The cabinet (1.3) houses the additional
basic components of the general computer system such as the
microprocessor, memory and disk drives. In a general computer system the
microprocessor is any commercially available processor of which x86
processors from Intel and 680X0 series from Motorola are examples. Many
other microprocessors are available. The general computer system could be
a single processor system or may use two or more processors on a single
system or over a network. The microprocessor for its functioning uses a
volatile memory that is a random access memory such as dynamic random
access memory (DRAM) or static memory (SRAM). The disk drives are the
permanent storage medium used by the general computer system. This
permanent storage could be a magnetic disk, a flash memory and a tape.
This storage could be removable like a floppy disk or permanent such as a
hard disk. Besides this the cabinet (1.3) can also house other additional
components like a Compact Disc Read Only Memory (CD-ROM) drive, sound
card, video card etc. The general computer system also includes various
input devices such as, for example, a keyboard (1.4) and a mouse (1.5).
The keyboard and the mouse are connected to the general computer system
through wired or wireless links. The mouse (1.5) could be a two-button
mouse, three-button mouse or a scroll mouse. Besides the said input
devices there could be other input devices like a light pen, a track
ball, etc. The microprocessor executes a program called the operating
system for the basic functioning of the general computer system. The
examples of operating systems are UNIX®, WINDOWS® and OS X®.
These operating systems allocate the computer system resources to various
programs and help the users to interact with the system. It should be
understood that the disclosure is not limited to any particular hardware
comprising the computer system or the software running on it.

[0075] FIG. 4 shows the internal structure of the general computer system
of FIG. 3. The general computer system (2.1) includes various subsystems
interconnected with the help of a system bus (2.2). The microprocessor
(2.3) communicates and controls the functioning of other subsystems.
Memory (2.4) helps the microprocessor in its functioning by storing
instructions and data during its execution. Fixed Drive (2.5) is used to
hold the data and instructions permanent in nature like the operating
system and other programs. Display adapter (2.6) is used as an interface
between the system bus and the display device (2.7), which is generally a
monitor. The network interface (2.8) is used to connect the computer with
other computers on a network through wired or wireless means. The system
is connected to various input devices like keyboard (2.10) and mouse
(2.11) and output devices like a printer (2.12) or speakers. Various
configurations of these subsystems are possible. It should also be noted
that a system implementing exemplary embodiments may use less or more
number of the subsystems than described above. The computer screen which
displays the recommendation results can also be a separate computer
system than that which contains components such as database 360 and the
other modules described above.

[0076] Referring now to FIGS. 11 and 12, and in accordance with an
illustrative embodiment of the invention, a mask to be worn on a
subject's face for use in respiratory monitoring and/or diagnostics will
be described. The mask, generally referred to using the numeral 1000,
comprises at least one transducer, such as microphones 1002 and 1004 in
this example, and a support structure 1006 for supporting same above a
nose and mouth area of the subject's face. The support structure 1006 is
generally shaped and configured to rest on the subject's face and thereby
delineate the nose and mouth area thereof (e.g. see FIG. 12), and
comprises two or more outwardly projecting limbs 1008 (e.g. three limbs
in this example) that, upon positioning the mask 1000, converge into a
transducer supporting portion 1010 for supporting microphones 1002 and
1004 at a distance from this area.

[0077] In general, the at least one transducer is responsive to sound
and/or airflow for generating a data signal representative thereof, so to
effectively monitor sound and/or airflow produced by the subject while
breathing. For example, in the illustrated embodiment, two microphones
1002 and 1004 are provided in the transducer support portion 1010,
wherein one of these microphones may be predominantly responsive to
sound, whereas the other may be predominantly responsive to airflow. For
example, the microphone configured to be predominantly responsive to
airflow may be more sensitive to air pressure variations then the other.
In addition or alternatively, the microphone configured to be
predominantly responsive to sound may be covered with a material that is
not porous to air. In addition or alternatively, the microphone
configured to be predominantly responsive to sound may be oriented away
from the subject's nose and mouth so to reduce an air impact on the
diaphragm of this microphone produced by the subject's breathing airflow.
In other embodiments, a microphone predominantly responsive to airflow
may be positioned in the transducer support portion in line with the
subject's nose and mouth, while another microphone may be positioned to
the side or on the periphery of the mask to thereby reduce an influence
of airflow thereon. In some of these embodiments, the recorded sound from
the peripheral microphone, or again from the microphone predominantly
responsive to sound, may in fact be used to isolate the airflow signal
recorded in the nosepiece, by filtering out the sound signal recorded
thereby, for example. An example of this process is schematically
depicted in FIG. 23, wherein a sound signal recorded via microphone 2 is
used as reference for microphone 1 to further isolate an airflow signal
picked up via microphone 1. It will be appreciated that this type of
processing may occur locally, via one or more microprocessors disposed
directly within the mask, for example, or again via a downstream
processing platform, for example implemented at a remotely located
diagnostic center.

[0078] In yet another embodiment, a single microphone may alternatively be
used to capture both sound and airflow, wherein each signal may be
distinguished and at least partially isolated via one or more signal
processing techniques, for example, wherein a turbulent signal component
(e.g. airflow on microphone diaphragm) could be removed from other
acoustic signal components (e.g. snoring). Such techniques could include,
but are not limited to adaptive filtering, harmonics to noise ratio,
removing harmonics from a sound recording, wavelet filtering, etc.

[0079] In each of the above examples, the device may be implemented using
a single type of transducer, for example one or more microphones which
may in fact be identical. It will be appreciated however that other types
of transducers, particularly responsive to airflow, may be considered
herein without departing from the general scope and nature of the present
disclosure. For example, a pressure sensor or airflow monitor may be used
instead of a microphone to yield similar results in capturing an airflow
produced by the subject while breathing.

[0080] Furthermore, while the above examples contemplates the provision of
one or more transducers for the recordal of both sound and airflow, it
may be desirable, in accordance with other embodiments of the invention,
to include only a single transducer for acquiring data representative of
only one of sound or airflow. For example, in the illustrative
embodiments depicted and described in greater detail below, improved
airflow measurements may in fact be used in isolation to provide a
certain level of monitoring and diagnosis, without departing from the
general scope and nature of the present disclosure.

[0081] It will also be appreciated by the skilled artisan that the exact
location of the transducer(s)/microphone(s) may, depending on the
subject, application and/or further experimentation, be subject to
change. For example, the mask may be reconfigured to adjust the position
of the at least one transducer, together or independently when
considering multiple-transducer embodiments, to be closer to the nose,
closer to the mouth, between the nose and mouth, in the upper lip or
mustache area of the subject's face, etc. Ultimately, the mask will
provide for the ability to capture both sound and airflow, both useful in
respiratory monitoring and diagnostics.

[0082] Still referring to the embodiment of FIGS. 11 and 12, the support
structure further comprises an optional frame 1012 and face resting
portion 1014 shaped and configured to contour the face of the subject and
at least partially circumscribe the nose and mouth area of the subject's
face, thereby facilitating proper positioning of the mask on the
subject's face and providing for greater comfort. A restraining
mechanism, such as head straps 1016 and 1018, can be used to secure the
mask to the subject's face and thereby increase the likelihood that the
mask will remain in the proper position and alignment during use, even
when the subject is sleeping, for example, in monitoring and diagnosing
certain common breathing disorders. It will be appreciated that the mask
and diagnostic approaches described below are also applicable, in some
conditions, in monitoring and diagnosing a subject's breathing when
awake.

[0083] In this embodiment, the mask 1000 further comprises a recording
device 1020, such as a digital recording device or the like, configured
for operative coupling to the at least one transducer, such as
microphones 1002 and 1004, such that sound and/or airflow signals
generated by the at least one transducer can be captured and stored for
further processing. In this particular embodiment, the recording device
1020 is disposed on a frontal member 1022 of the support structure 1006,
thereby reducing an obtrusiveness thereof while remaining in close
proximity to the at least one transducer so to facilitate signal transfer
therefrom for recordal. In providing an integrated recording device, the
mask 1000 can effectively be used as a self-contained respiratory
monitoring device, wherein data representative of the subject's breathing
can be stored locally on the mask and transferred, when convenient, to a
remotely located respiratory diagnostic center.

[0084] As discussed hereinabove, breathing disorders are traditionally
monitored and diagnosed using data acquired at sleep centers, where
subjects are fitted with a number of electrodes and other potentially
invasive monitoring devices, and monitored while they sleep. Clearly, as
the subject is both required to sleep in a foreign setting with a number
of relatively invasive and obtrusive monitoring devices attached to them,
the data collected can often be misleading, if the subject even ever
manages to get any sleep to produce relevant data. Clearly, other
respiratory monitoring and diagnostic approaches can be implemented while
the subject is awake, and such approaches are fully within the realm of
the present disclosure as the masks and methods disclosed herein may, in
some embodiments, be rendered equally useful in monitoring or diagnosing
sleeping and awake subjects.

[0085] Furthermore, known respiratory diagnostic systems, for example as
depicted in FIG. 24, generally require the acquisition of multiple
sensory data streams to produce workable results that may include breath
sounds, airflow, chest movements, esophageal pressure, heart rate, etc.
Similarly, known portable monitoring devices proposed for the diagnosis
of sleep apnea generally require subjects to adequately position and
attach several wired electrodes responsive to a number of different
biological parameters, such as listed above, which generally reduces the
comfort and compliance of subjects and increases chances of detachment
and/or displacement of the electrodes. Given that portable sleep apnea
monitors are used in the absence of an attending health care
professional, inaccurate placement or displacement of electrodes cannot
be easily detected until the data is transferred to the health center. On
the other hand, simplified portable respiratory monitoring devices, as
discussed above, only produce data with respect to either airflow or
sounds generated during breathing, which limited data sets are generally
insufficient in adequate respiratory disorder diagnostics.

[0086] In comparison, the respiratory monitoring and/or diagnostic mask
described above in accordance with one embodiment of the invention may
provide a number of advantages over known techniques. For example, all
elements of this self-contained diagnostic mask are contained in a single
unit including for instance, the at least one transducer, power supply,
electronics, and data storage. The at least one transducer is embedded
within the mask structure and thus readily positioned on the subject's
face by the very nature of the mask's spatial configuration. Accordingly,
proper positioning is generally guaranteed, allowing for adequate capture
of both sound and airflow produced by the subject while breathing, while
reducing the number of required electrodes. Furthermore, as all wiring
and circuitry is embedded within the mask, problems traditionally
associated with disconnection of sensory electrodes are practically
eliminated. The subject is also free of external wiring, thereby reducing
subject discomfort and increasing compliance. This advantage is
diagrammatically illustrated in FIG. 24, wherein a single physical data
channel can be produced locally using the self-contained mask, and
communicated to a diagnostic center where signal processing, for example
as described below, enables extraction of a number of clinical measures
useful in providing similar diagnostics as that only previously available
using multiple electrodes in conventional systems. It will be appreciated
that reducing the number of physical channels provides great advantage in
deploying a portable device wherein a layman is required to wear the
device in the absence of a trained health care provider. In the present
diagram, it will be appreciated that reference to a "single channel" in
fact generally represents a single physical link between the subject, and
what could ultimately result in a full respiratory diagnosis. Namely, the
subject in this embodiment is only requested to wear a mask which allows
for recordal of both sound and airflow via one or more transducers, while
allowing for the downstream processing of multiple clinical measures from
this single data acquisition device. To the contrary, clinical and known
portable devices generally require multiple data outputs provided by a
multiplicity of data acquisition devices so to access multiple clinical
measures, which, as discussed above, reduces subject comfort and
compliance, and may therefore reduce data reliability and
reproducibility. The alternative in the art, is to reduce data
acquisition to a single measure, which, in general, has limited value.

[0087] In one embodiment, the recorded data is stored, and optionally
encrypted on a removable data storage device, such as an SD card or the
like. For example, analog data acquired by the one or more transducers
can be locally pre-amplified, converted into digital data (e.g. via a
local A/D converter) and stored in the removable memory device. The
stored data can then either be uploaded from the memory card to a local
computing device (e.g. laptop, desktop, palmtop, smartphone, etc.) for
transmittal to a remotely located diagnostic center via one or more wired
and/or wireless communication networks, or physically shipped or
delivered to the remotely located diagnostic center for processing.
Namely, the acquired data can be processed via one or more diagnostic
software platforms, or the like (e.g. as discussed hereinbelow), to
evaluate the subject's breathing and provide, as appropriate, diagnosis
of relevant breathing disorders. Furthermore, given this system's
generally distributed architecture, various distinct and/or complimentary
processing techniques and algorithms may be applied to a same data set to
increase diagnostic complexity and/or reliability, for example. In such
embodiments, given that the data storage device retains all relevant
data, once the data is shipped, the mask itself may be disposed of, or
again, reused by the same subject to acquire further data in respect of a
same or similar breathing study.

[0088] It will be appreciated that different types of data transfer and
communication techniques may be implemented within the present context
without departing from the general scope and nature of the present
disclosure. For example, while the above example contemplates the use of
a digital recording device having a removable data storage medium, such
as a memory card of the like, alternative techniques may also be
considered. For example, the recording device may rather include a
wireless communication interface wherein data integrally recorded thereon
can be wirelessly uploaded to a computing device in close proximity
thereto. For example, Wi-Fi or Bluetooth applications may be leveraged in
transferring the data for downstream use. Alternatively, the device may
include a communication port wherein recorded data may be selectively
uploaded via a removable communication cable, such as a USB cable or the
like. In yet another example, the recording device itself may be
removably coupled to the mask and provided with a direct communication
interface, such as a USB port or the like for direct coupling to an
external computing device. These and other such examples are well within
the realm of the present disclosure and therefore, should not, nor should
their equivalents, be considered to extend beyond the scope of the
present disclosure.

[0089] As will be appreciated from the proposed diagnostic procedures
described below, the provision of a respiratory monitoring and diagnostic
mask, as described herein, provides for the implementation of a method
for remotely diagnosing a breathing disorder of a subject. Namely, upon
providing the subject access to a self-contained mask, as described
herein, the subject may then proceed to wear the mask, when appropriate
for the condition to be monitored, and integrally record both sound and
airflow produced during breathing. Once this data is transferred to a
remotely located diagnostic center, a breathing disorder may be diagnosed
on the basis of the processed sound and airflow signals recorded by the
mask. Namely, no additional sensors or recordings are required to achieve
workable results, leaving the subject to conduct all relevant recordings
at home, if so desired, remote from any qualified health care
practitioner. Furthermore, the general improvements in transducer
positioning achieved by the design of the various embodiments of the
masks described herein, allow for greater data reliability and
reproducibility, while significantly reducing and discomforts or
inconveniences to the subject.

[0090] Referring now to FIGS. 13 to 22, the general shape and structural
features of support structure 1006, in accordance with one embodiment of
the invention, will be described in greater detail. In this embodiment,
the support structure comprises three (3) outwardly projecting limbs,
namely two opposed limbs 1050 and a central limb 1052, which converge
into the transducer supporting portion 1010, thereby forming a
tripod-like structure extending from the nose and mouth area of the
subject's face when the mask is in position. Each of these limbs has,
along at least a portion thereof and in accordance with one embodiment,
an inward-facing channel 1054 defined therein for channeling at least a
portion of airflow produced by the subject while breathing, toward the at
least one transducer disposed within the transducer supporting portion
1010. To further accentuate this feature, the transducer supporting
portion 1010 of this particular embodiment is shaped and oriented to
further funnel the airflow channeled by the limbs 1050 and 1052 toward
the at least one transducer, depicted generically in FIG. 21 as
transducer 1056. For instance, the funneling shape may fluidly extend
into each of these inward-facing channels 1054 to provide a continuous
airflow guide toward the at least one transducer 1056 positioned within
the transducer support portion 1010. Furthermore, as will be appreciated
by the person of ordinary skill in the art, the provision of limbs 1050
and 1052, as compared to an enclosed mask, provides for reduced airflow
resistance, resulting in substantially reduced dead space.

[0091] As will be appreciated by the person of ordinary skill in the art,
the general shape and design of the above-described mask can provide, in
different embodiments, for an improved responsiveness to airflow produced
by the subject while breathing, and that irrespective of whether the
subject is breathing through the nose or mouth. Namely, the ready
positioning of an appropriate transducer responsive to airflow relative
to the nose and mouth area of the subject's face is provided for by the
general spatial configuration of the mask. Accordingly, great
improvements in data quality, reliability and reproducibility can be
achieved, and that, generally without the assistance or presence of a
health care provider, which is generally required with previously known
systems.

[0092] Furthermore, it will be appreciated that different manufacturing
techniques and materials may be considered in manufacturing this and
similar masks, without departing from the general scope and nature of the
present disclosure. For example, the entire mask may be molded in a
single material, or fashioned together from differently molded or
otherwise fabricated parts. For example, the outwardly projecting
nosepiece of the mask may comprise one part, to be assembled with the
frame and face-resting portion of the mask. Alternatively, the frame and
nosepiece may be manufactured of a single part, and fitted to the
face-resting portion thereafter. As will be further appreciated, more or
less parts may be included in different embodiments of the mask, while
still providing a similar result. For example, the nose piece, or an
equivalent variant thereto, could be manufactured to rest directly on the
subject's face, without the need for a substantial frame or face resting
portions, as illustrated in the above described embodiments.
Alternatively or in addition, different numbers of limbs (e.g. two,
three, four, etc.) may be considered to provide similar results, as will
be appreciated by the person of ordinary skill in the art.

[0093] In accordance with another embodiment, a microphone 12 is located
in a position proximal to an individual's mouth as shown in FIGS. 2a and
2b, in this case by a dimension A of approximately 3 cm in front of the
individual's face, i.e. at a distance from a nose and mouth area of the
subject's face. The microphone 12 may be configured to communicate with
the microprocessor by way of an interface or other data acquisition
system, via a signal transducing link or data path 18 to provide one or
more data collection modules with the microphone 12. Thus, such data
collection modules and the microphone are operable to collect breathing
sounds emanating from the individual's mouth and nose, during the
inspiration and/or expiration phases of breathing. For example, an
exemplary microphone response curve is shown in FIG. 1. The acoustic
signal data breathing sounds collected from the individual may be
comprised of both airflow sounds from the individual's breathing applying
air pressure to the microphone diaphragm and actual breathing sounds
resultant from the individual's breathing being recorded and/or collected
by the microphone 12. Furthermore, the acoustic signal data breathing
sounds collected from the individual may be, in another exemplary
embodiment, comprised of substantially only actual sounds resultant from
the individual's breathing being recorded and/or collected by the
microphone 12. In still yet another embodiment, the acoustic signal data
breathing sounds collected from the individual may be comprised of
substantially only airflow sounds resultant from the individual's
breathing applying air pressure to the microphone diaphragm and being
recorded and/or collected by the microphone 12. As used herein, term
"airflow sounds" refers to the air pressure resultant from an
individual's breathing being applied to and causing the microphone's
diaphragm to move such that the microphone collects and produces data for
the audio recording.

[0094] The microphone 12, for example, may be coupled in or to a loose
fitting full face mask 16 as shown in FIGS. 2a and 2b. Furthermore, the
face mask 16 may include at least one opening 14 to allow for ease of
breathing of an individual 20. For example, the microphone 12 may be in a
fixed location with a spacing of dimension "A", of about 3 cm in front of
the individual's face as shown schematically in FIG. 2a; however other
distances in front of the individual's face may be desirable in some
embodiments. The microphone 12, in this case, is embedded in a
respiratory mask 16 which is modified by cutting away material so as
produce opening 14 such that only a structural frame portion remains to
keep the microphone 12 in a fixed location relative the nostrils and the
mouth of an individual 20. In one example, the audio signals from the
microphone may be digitized using an audio signal digitizing module and
digitized sound data to be transferred via transducing link 18 to the
computer using a USB preamplifier and audio interface (M-Audio, Model
Fast Track Pro USB) with a sampling rate of 22,050 Hz and resolution of
16 bits. Although various types of audio interfaces may be used, in the
instant exemplary embodiment, an external audio interface provides
suitable results over the other types of audio adapters, for example,
built-in audio adapters due to the superior signal to noise (S/N) ratio
of the external adaptor which is about 60 dB at 1 kHz. Sound recordings
may then be passed through a 4th order band-stop digital filter with
a centre frequency of about 60 Hz to suppress line interference. Other
structures may also be used to locate the microphone in position, as
including support structures positioned against a plurality of locations
on the individual or stationed adjacent the individual as required.

[0095] Furthermore, in another exemplary embodiment, a two microphone
system may be useful. In such a system, as shown in FIG. 2b, one of the
microphones, a first microphone 12b, may be configured to collect actual
breathing sounds and airflow sounds whereas the other microphone, a
second microphone 12c may be configured to collect substantially only
actual breathing sounds. In this embodiment, the waveform sounds and/or
data collected from the second microphone 12c may be subtracted or
filtered from the waveform sounds collected from the first microphone
12b, thereby resulting in a waveform data stream of substantially only
airflow sounds. The airflow sounds may be resultant of pressure air from
an individual's breathing being collected as applied to the diaphragm of
a microphone as noted above. Subsequently, the airflow sounds may then be
used as a waveform amplitude acoustic data stream in accordance with the
forgoing method.

[0096] A raw acoustic data stream of breathing sounds, as shown in a
representative plot, for example in FIG. 5, is then collected for each of
a plurality of respiratory phases to form a bioacoustics signal
recording, wherein the acoustic data stream is subsequently transformed.

[0097] As will be described below, in at least one embodiment, a method
and an apparatus are provided to monitor, identify and determine the
inspiratory and/or expiratory phases of the respiratory cycle of an
individual 20 from the frequency characteristics breathing sounds. It is
understood that a numerical comparative analysis of the frequency
spectrum as transformed from waveform amplitude data of breathing sounds
and/or airflow sounds of an individual 20 may be useful to differentiate
between the inspiration and expiration phases of breathing.

[0098] It will be appreciated by the person of ordinary skill in the art
that while the below example describes a method in which a mask as
depicted in FIGS. 2a and 2b was used for data acquisition and breath
monitoring/diagnostics, a mask as described above with reference to FIGS.
11 to 22 could also be used to produce similar effects, and that, without
departing from the general scope and nature of the present disclosure.
Furthermore, while the below predominantly proposes a wired solution for
real-time monitoring, a similar approach may be applied, for example with
respect to a self-contained mask as described above, wherein processing
steps applied to the locally acquired data could be implemented remotely
at an appropriate diagnostic center.

Data Acquisition

[0099] Data were collected from 10 consecutive men and women at least 18
years of age referred for overnight polysomnography (PSG). The subjects'
characteristics are shown in Table 1. Breath sounds were recorded by a
cardoid condenser microphone (Audi-Technica condenser microphone, Model
PRO 35x). The microphone's cardioid polar pattern reduces pickup of
sounds from the sides and rear, improving isolation of the sound source.
The microphone 12 used for recording breath sounds has a relatively flat
frequency response up to 2000 Hz as shown in FIG. 1. Furthermore, the
microphone 12, as used herein has a higher output when sound is
perpendicular to the microphone's diaphragm as shown by the solid line in
FIG. 1, which helps reduce low frequency ambient noise interference. In
this example, the microphone 12 was embedded in the centre of a loose
fitting full face mask 16 modified to reduce airflow resistance and
eliminate dead space by way of large openings 14 as shown in FIGS. 2a and
2b. The microphone 12 attached to the face mask 16, and was located in
front of the individual's face. The mask 16 provides a structural frame
portion to keep the microphone in a fixed location, at a dimension A of
approximately 3 cm in front of the individual's face, so as to record
breathing sounds to an audio recording device, such as a computer as
described above, to make an audio recording thereof. In some exemplary
embodiments, the audio recording of breathing sounds may be made and
recorded in analog format prior to digitizing the audio recording.
However, in other embodiments the audio recording of breathing sounds may
be digitized in real-time. Furthermore, in some exemplary embodiments,
the processing of the audibly recorded waveform data or acoustic signal
data may be performed in real-time, so as to provide substantially
instantaneous information regarding an individual's breathing. In an
exemplary embodiment, digitized sound data were transferred to a computer
using a USB preamplifier and audio interface (M-Audio, Model MobilePre
USB) with a sampling rate of 22,050 Hz and resolution of 16 bits.
Although various types of audio interfaces may be used, in the instant
exemplary embodiment, an external audio interface was preferred over a
built-in audio adapter due to the better signal to noise (S/N) ratio of
the external audio interface, which was 91 dB. FIG. 5 shows a 25-second
waveform amplitude recording plot. However, in other exemplary
embodiments, it may be desirable to record breathing sounds for a time
period of from about 10 seconds to 8 hours. In some exemplary embodiments
it may be desirable to record breathing sounds for a time period of from
about 10 second to about 20 minutes. In other exemplary embodiments, it
may be desirable to record breathing sounds for greater than 20 minutes.

Breathing Acoustics Analysis

[0100] In an exemplary embodiment, full night breath sound recordings were
displayed on a computer screen similar to the computer screen 1.2 of FIG.
3. A representative raw acoustic data waveform plot, as may be shown on a
computer screen 1.2, is provided in FIG. 5 for a 25-second recording.
Each increase in amplitude represents a single breath. The individual
phases of a breathing cycle are not readily resolvable in FIG. 5 owing to
the time scale being too large to resolve single breath details. For
example, FIG. 7a more clearly shows the inspiration and expiration phases
of a breathing cycle in a waveform amplitude versus time plot. The
recordings were visually scanned to identify periods of regular
breathing. After visual scanning, the recordings were played back for
auditory analysis.

[0101] Sequences of normal breaths that did not have signs of obstructive
breathing such as snoring and interruptions, or other irregularities such
as tachypnea (rapid breathing), or hyperventilation (deep breathing) were
then included in the subsequent frequency analysis. However, snoring and
other types of noisy breathing can also be included in this analysis by
applying a pre-processing technique that isolates turbulent from
non-turbulent components, (e.g. as shown in FIG. 23) whereby ultimately,
the turbulent component may be selected for further processing. This
process was repeated to select three random parts of an individual's
sleep. If a portion of the recording fulfilled the aforementioned
inclusion criteria, then 3 to 4 consecutive breaths were selected from
that portion. A total of 10 breaths were selected from each individual.
During the process of selecting the individual's breathing sound
portions, the investigator did not have a previous knowledge of the sleep
stage. Therefore, the investigator was blind to the sleep stage of an
individual while selecting the analyzed breaths except for knowing that
sampling started after the onset of sleep. The real-time stamp of each
breath was registered in order to retrieve the sleep stage in which it
took place in afterwards. Subsequently, the investigator listened to
these breathing sounds again to divide each breath into its inspiratory,
expiratory and interbreath phases. Each phase was labeled manually.

[0102] The data array of each breathing phase was passed through a hamming
window and a 2048-point Fast Fourier Transform (FFT) of the windowed data
with 50% overlap was calculated. The resultant frequency spectrum was
displayed on a computer screen for visual analysis. The frequency spectra
of the interbreath pauses were also calculated and incorporated in the
analysis to control for the effect of ambient noise. Careful visual
examination of spectra revealed that during inspiration, the amplitude of
signals above 400 Hz was consistently higher than during expiration.
Therefore, it was determined that the bands ratio (BR) of frequency
magnitude between 400 to 1000 Hz, to frequency magnitude between 10 to
400 Hz is higher in the inspiration phase as compared to the expiration
phase. It will be appreciated that the above-noted threshold of 400 Hz is
not necessarily to be strictly applied as this value can be varied
generally between 200 Hz and 900 Hz depending on the microphone acoustic
characteristics, and specificities of the application. The BR of each
breathing cycle was then calculated using equation (1).

[0103] Using equation (1), the numerator represents the sum of FFT higher
frequency magnitude bins which lie between 400 and 1000 Hz, and the
denominator represents the sum of FFT lower frequency magnitude bins
which lie between 10 and 400 Hz. Bins bellow 10 Hz were not included to
avoid any DC contamination (referring to drift from a base line), and
frequencies above 1000 Hz, can also, in some embodiments, be neglected
since preliminary work (not shown) revealed insignificant spectral power
at frequencies above 1000 Hz, in which case the computation may also be
reduced. It will be appreciated, however, that higher frequencies above
1000 Hz may nonetheless be included depending on the calculation power of
the instruments being used. To verify repeatability of the results, BR
was calculated for 3 to 4 successive breaths in the included sequence and
for a total of three sequences from different parts of the individual's
sleep. A total of 100 breaths were collected from the 10 subjects. The
mean number of breaths per subject was 10±0.

[0104] It will be appreciated by the person of ordinary skill in the art
that other methods may be employed to achieve similar results. For
example, while taking the ratios of sub-bands of an FFT spectrum to
measure sub-band energy distributions provides a useful approach, other
statistical methods and pattern recognition tools can be used to
distinguish the relative distribution of sub-band ratios in FFT.
Furthermore, FFT could also be replaced, in some embodiments, by
implementing a series of digital filters that measure signal energy in
the bands mentioned in this work, for example. Additionally, it will be
appreciated that the entire digital processing stream, could, in some
embodiments, be replaced by analogue signal processing techniques, such
as by deploying a series of analog filters to achieve similar results.

Sleep Staging

[0105] Sleep stages were recorded during the course of the night using
standard polysomnographic techniques that included
electro-encephalography (EEG), electro-oculography and submental
electro-myography (Rechtschaffen A and Kales A 1968 A Manual of
Standardized Terminology, Techniques and Scoring System for Sleep Stages
of Human Subjects. (Los Angeles: UCLA Brain Information Service/Brain
Research Institute). The corresponding sleep stage for the selected
breath samples was determined from the PSG recording (not shown).

[0107] Healthy subjects at least 18 years of age were recruited with no
history of respiratory or cardiopulmonary disease in addition to being
free from prescribed medications. Data were collected from 15 subjects, 6
men and 9 women, healthy volunteers. Individuals used in the study were
recruited by advertisement and were divided randomly intro 2 groups with
5 subjects in one group (test group) and 10 in the other (validation
group). The data from the 5 subjects in the test group were used to
examine acoustic characteristics of breathing phases, which were then
incorporated into a method having an algorithm as described below. The
resultant method was tested on the data of 10 subjects in the validation
group to determine the validity of the method for determining the
inspiration and expiration phases of an individual's breathing sounds.

Breath Sound Recording

[0108] Breath sounds in this particular example were recorded using a
unidirectional, electret condenser microphone (Knowles Acoustics, Model
MB6052USZ-2). The microphone's unidirectional pattern reduces the pickup
of sounds from the sides and rear thereby improving isolation of the
sound source. In this example, the microphone 12 was embedded in a
respiratory mask 16, as shown in FIGS. 2a and 2b, that was modified by
cutting away material so as to produce opening 14 such that only a
structural frame remained to keep the microphone 12 in a fixed location
relative the nostrils and the mouth of an individual 20 at a dimension
"A" of approximately 3 cm in front of the individual's face as shown in
FIG. 2a. The audio signal was digitized using an audio signal digitizing
module and digitized sound data were transferred via transducing link 18
to a computer using a USB preamplifier and audio interface (M-Audio,
Model Fast Track Pro USB) with a sampling rate of 22,050 Hz and
resolution of 16 bits. Although various types of audio interfaces may be
used, in the instant exemplary embodiment, an external audio interface
was preferred over the other types of audio adapters, for example,
built-in audio adapters due to the superior signal to noise (S/N) ratio
of the external adaptor which was about 60 dB at 1 kHz. Sound recordings
were then passed through a 4th order band-stop digital filter with a
centre frequency of about 60 Hz to suppress line interference.

Respiratory Inductance Plethysmography

[0109] Respiratory inductance plethysmography (RIP), (Respitrace
Ambulatory Monitoring Inc., White Plains, N.Y., USA) was used to monitor
respiratory pattern of individuals and the timing of the breathing
phases. In contrast to other breathing monitoring apparatus such as
pneumotacography, RIP has the advantage of being applied away from the
face of an individual to allow capture of breathing phases. Briefly, RIP
is a system comprising two flexible sinusoidal wires. Each wire is
embedded in stretchy fabric band. One band 28 is placed around the chest
of an individual and the other band 30 is placed around the abdomen of
the individual as shown in FIG. 6a. The inductance of each band changes
upon rib cage and abdomen displacements and generates a voltage signal
proportional to its inductance. The signals from the RIP bands 28 and 30
were digitized at 150 Hz and stored in a computer memory as substantially
describe above with reference to FIGS. 3 and 4. The electrical sum of the
ribcage and abdominal signals is displayed on a readable medium, for
example a computer screen or a physical plot, and provides the total
thoracoabdominal displacement. The thoracoabdominal displacement recorded
from the RIP system reflects changes of tidal volume during respiration.

[0110] In order to compare the inspiration and expiration phases of an
individual's breathing to RIP, the microphone 12, as noted above, was
coupled in this example to a modified mask 16 in front of the subject's
face. Simultaneously, the RIP bands 28 and 30 were placed around the
subject's chest and abdomen to measure thoracoabdominal motion as noted
above. Recording were captured from both the microphone 12 and the RIP
bands 28 and 30 simultaneously to assess the timing of breath sounds
against the RIP waveform data.

Study Protocol

[0111] Individuals were studied in the supine position and were instructed
to breathe normally. Microphone holding frame 16 was placed on
individual's face. Each individual was asked to breath for two minutes at
their regular breathing rate. In order to mimic all possible breathing
conditions, the individuals were asked to breath through their nose only
for half of the experiment time, and through their nose while mouth was
slightly open in the other half Incomplete breaths at the beginning and
end of recording were discarded and all the breaths in between were
included in the analysis.

Analysis of Breath Acoustics

[0112] In a first stage, spectral variables of breath sounds that
characterize the inspiratory and expiratory phase components of a
respiratory cycle were determined. The data of five subjects, 3 females
and 2 males was chosen randomly from total 15 subjects and used to study
the frequency characteristics of the acoustic signals of different
respiratory phases. Inspiratory and expiratory segments of breath sounds
were determined and extracted from the acoustic data by comparing it to
the inspiratory (rising edge) and expiratory (falling edge) of the RIP
trace as shown in FIG. 6b. A 25-second long recording of breath sounds
and simultaneous summed thoracoabdominal RIP signals from a
representative subject is shown, for example, in FIG. 6b. Dashed vertical
lines are shown to separate inspiration and expiration phases of the
second cycle at 32.

[0113] The first 10 complete breaths of each subject were analyzed, which
yielded a total of 50 inspirations and 50 expirations acoustic data sets
from the 5 subjects. Subsequently, the frequency spectrum of each phase
was calculated separately using Welch's method (i.e. the average of a
2048-point Fast Fourier Transform (FFT) of sliding hamming windows with
50% overlap). FFT arrays were normalized in amplitude in order to compare
the relative changes in power spectrum among resultant spectral arrays.

[0114] Using variables derived from frequency spectra of the 5 test
individual's noted above, the inspiratory and expiratory phases of the
breathing cycle were determined for the remaining 10 individuals in order
to test the validity of the method. Furthermore, the method was tested
for the ability to determine breathing phases from acoustic data
independently from other inputs. The data analysis was performed with
Matlab R2007b software package (Mathworks, Natick, Mass.).

Results

[0115] The characteristics of the individuals in this study are shown in
Table 1. A total of 100 breaths were sampled from 10 patients with a mean
number of 10 breaths per subject. Seventy percent of the breaths analyzed
were from non-rapid-eye movement sleep (NREM), and 18% from rapid eye
movement sleep (REM), and 12% while patients were awake according to the
polysomnographic criteria.

[0117] As shown in a representative example in FIG. 7b, there was a sharp
narrow band of harmonics usually below 200 Hz for inspiration. The
spectrum exhibited a valley between 200 Hz and 400 Hz and a peak again
after 400 Hz as shown in FIG. 7b. Another variation of the inspiratory
spectrum was the same initial narrow band followed by a relatively smooth
spectrum without the 400 Hz drop (not shown). The expiratory spectrum, as
shown in a representative example in FIG. 7c, on the other hand, formed a
wider band that spanned frequencies up to 500 Hz and whose power dropped
off rapidly above this frequency. The inspiratory spectrum (FIG. 7b)
showed a peak close to the line frequency. The spectrum of the
interbreath pause (not shown) was inconsistent and showed random
variations without any consistent pattern. To rule out the effect of line
frequency on inspiration bands ratio (BRi), a Wilcoxon signed rank test
was used to test the relation between BRi and bands ratio interbreath
pause (BRp). The test was significant (p<0.001), thus it was
determined that BRi is different from BRp and that line interference does
not significantly contribute to the frequency spectrum of inspiration.

[0118] The relationship between BRi and BRe was examined using the
Wilcoxon Signed Ranks Test. The test showed that a BRi is not equal to
BRe (P<0.001) with 95% of breathes having BRi greater than BRe. Since
minute differences between BRi and BRe might be attributed to randomness,
two thresholds of 50% and 100% difference between BRi and BRe were
tested. The ratio BRi/BRe was calculated for each breath. By taking the
ratio, BRi and BRe may be treated as dependant pairs. These ratios were
then tested for being greater than 1.5 (50% difference) and greater than
2 (100% difference). The one-sample sign test showed that BRi/BRe is
greater than 1.5 (p<0.001) and greater than 2 (p<0.001). In order
to account for potential differences between subjects in the analysis,
the mean BRi/BRe was calculated for each individual subject as displayed
in Table 2. The one-sample sign test of the median was significant for
mean BRi/BRe greater than 1.5 (p=0.001) and significant for mean BRi/BRe
greater than 2 (p=0.001). Breaths that were drawn when subjects were
polysomnographically awake did not differ significantly in terms of
BRi/BRe from the rest of breaths (p=0.958) and, therefore, were included
in the aforementioned analysis.

[0119] The sensitivity of this method was tested for each of the two
cut-offs. Out of 100 breath samples, 90 had BRi 50% greater than BRe, and
72 had BRi 100% greater than BRe thereby giving an overall sensitivity of
90% and 72% respectively.

[0120] A total of 346 breaths met the inclusion criteria. The average
number of breaths per individual was 23.0±7.79. Only the first 10
complete breaths were used to study the spectral frequency
characteristics from the 5 individuals in the test group. From the
validation group 218 breaths (i.e. 436 phases) were included in the
analysis with an average of 21.8±8.2 breaths per subject.

Analysis of Breath Sounds

[0121] Data obtained from the test group of 5 individuals yielded 100
arrays of FFT magnitude bins normalized in amplitude with one half being
from inspiratory acoustic inputs or phases and the other half from
expiratory acoustic inputs or phases. The average spectrum of all
normalized arrays belonging to the inspiration and expiration phases with
the corresponding standard deviation are shown in FIGS. 8a and 8b
respectively. FIGS. 8a and 8b demonstrate that the frequency spectra of
the 2 phases have different energy distributions. The mean inspiratory
spectrum, shown in FIG. 8a peaked between 30 Hz and 270 Hz. The spectrum
exhibited flatness between 300 Hz and 1100 Hz before the next major peak
with a center frequency of 1400 Hz. The expiratory spectrum, on the other
hand, peaked between 30 to 180 Hz as shown in FIG. 8b. Its power dropped
off exponentially until 500 Hz after which it flattened at low power.

[0122] The signal power above 500 Hz was consistently higher in
inspiration than expiration. Since the ratio of frequency magnitudes
between 500 to 2500 Hz, the higher frequency magnitude bins, to frequency
magnitude between 0 to 500 Hz, the lower frequency magnitude bins, is
higher during the inspiration phase than during the expiration phase for
each breathing cycle, frequency ratio can be used to differentiate the
two phases of the breathing cycle. This ratio is presented in equation
(2) as the frequency bands ratio (BR).

[0123] The numerator of equation (2) represents the sum of FFT higher
magnitude bins between 500 to 2500 Hz, and the denominator represents the
sum of FFT lower magnitude bins below 500 Hz. BR was calculated for each
of the six curves shown in FIGS. 8a and 8b which include the curve of the
mean and the positive and negative standards deviation for both
inspiration and expiration. These results are presented in Table 3:

[0124] The numbers in Table 3 represent the BR which is a ratio calculated
from various curves.

[0125] Table 3 shows that the mean BR for inspiration (BRi) is 15.1 times
higher than mean BR for expiration (BRe). BRi is higher than that for
BRe. For example, by comparing the two extremes, `BR for mean
inspiration-Std`, and `BR for mean expiration+Std`, as noted in Table 3
and shown in FIGS. 8a and 8b, BRi may be 10.2 time greater than that for
BRe. However, other predetermined multipliers may be acceptable for
determining the inspiration and expiration phases of breathing. For
example, the multiplier maybe from about 1 to about to about 20.
Therefore, the frequency-based variable BR may be used to distinguish the
various phases of a given breathing cycle.

[0126] In order to validate the results of the procedure as found using
the test group, the BR parameters as determined above were utilized to
track the breathing phases in the individuals in the validation group. A
method that depends on past readings of acoustic data was developed to
predict the current phase. A flow diagram of this method is shown
schematically in FIG. 9. For example, a benefit of using past values
rather than post-processed statistics is that the technique can be
adopted for real-time implementation. According to this exemplary
embodiment, the acoustic data stream is segmented into 200 ms segments.
However, it may be desirable for the segments to be of a length greater
than or less 200 ms. For example the segments may be from about 50 ms to
about 1 second. Preferably, the segments are from about 100 ms to about
300 ms. Each segment is then treated as described above in relation to
the test group. For example, Welch's method was applied to calculate
frequency spectrum and it's BR, a first bands ratio (first BR).
Subsequently the mean BR of the past 1.4 seconds (7 segments×200
ms) or the mean of all the past BR's, whichever is greater, was
calculated. Each newly found BR, said first BR, was then compared with
the past BR average or mean bands ratio. If the first BR is greater than
the mean BR by at least a predetermined multiplier, then it is labeled as
inspiration. The predetermined multiplier may be from about 1.1 to about
10. Preferably the multiplier is from about 1 to about 5. Most
preferably, the multiplier is from about 1.5 to 2. For example, if the
first BR is twice the past 1.4 seconds BR average (mean BR) then it is
labeled as inspiration. Likewise, if the first BR is less than mean BR by
at least a predetermined multiplier, then it is labeled as expiration.
Therefore, for example, a segment is labeled as expiration if the
corresponding BR is 2 times below the average of the past two segments.
FIG. 10a shows an exemplary representative plot of an embodiment of all
BR values calculated from the acoustic data with the corresponding RIP
for comparison. Visual examination shows that there is a correlation
between BR waveform and its RIP counterpart. Averaging of the BR's is
performed in order to smooth out intra-phase oscillations in BR such as
in the case of the BR curve at time 5-10 seconds seen in FIG. 10a

[0127] The method was tested prospectively on the breathing acoustic data
of 10 subjects in the validation group. The breathing phases found using
the presently described method as applied to the data of FIG. 10a are
shown in FIG. 10b. With reference to FIG. 10b, the dashed line represents
the respiratory or breathing phases found utilizing the currently
described method. Out of 436 breathing phases, 425 breathing phases were
labeled correctly, 8 phases were partially detected, and 3 phases were
labeled as being the opposite phases. Therefore, utilizing the method,
about 97.4% of the breathing phases were detected correctly using
acoustic data as compared with RIP trace.

[0128] With reference to FIG. 10b, the breathing cycles are shown as a
processed wave amplitude versus time plot. The processed wave amplitude
data are shown by the dashed line and indicate the respiration phase of
an individual's breathing. In an exemplary embodiment, the processed wave
amplitude versus time plot may be displayed on a display module such as
that shown in FIG. 3 at 1.1. The processed wave amplitude versus time
plot may also be, in some exemplary embodiments, provided to an operator
by way of an information relay or relaying module in a printed form or
other suitable form, for example audio cues, such that the breathing of
an individual may be monitored in accordance with the method by an
operator. In some exemplary embodiments, the information relay module may
display or provide the processed data in terms or inspiration and/or
expiration indicia.

[0129] The frequency spectrum of inspiration may be characterized by a
narrow band below 200 Hz, a trough starting from about 400 Hz to about
600 Hz. In the exemplary embodiments noted herein, the trough begins at
about 400 Hz in one, the first, embodiment (FIG. 7b) and at about 500 Hz
in another, second, embodiment (FIG. 8a). A wider but shorter peak above
may be seen at about 400 Hz to about 600 Hz. The peak is seen at about
400 Hz in the first embodiment (FIG. 7b) and at about 500 Hz in the
second embodiment (FIG. 8a). In the embodiments noted herein, a smooth
frequency distribution is noted after the decline of the initial narrow
peak (FIGS. 7b and 8a). However, it maybe desirable in order embodiment
to utilize various other frequencies and frequency ranges, for example by
way of illustration and not limitation, greater than or less than about
400 Hz or 500 Hz.

[0130] Expiration, on the other hand, may be characterized by a wider peak
with a relatively sharp increase from about 10 to 50 Hz and a smooth drop
from about 50 to 400 Hz as seen in the first embodiment shown in FIG. 7c
or in the second exemplary embodiment as shown in FIG. 8b, above about
500 Hz. There is a relatively sparse frequency content above about 400 Hz
in the first exemplary embodiment of FIG. 7c and likewise in the
exemplary second embodiment of FIG. 8b above about 500 Hz. A cut-off
point of 400 Hz in the first exemplary embodiment and 500 Hz in the
second exemplary embodiment was chosen to distinguish between inspiration
and expiration phases based upon these observations. Although recordings
of breathing sounds have frequency content up to 10 kHz, most of the
power lies below 2 kHz, and therefore higher frequencies may not be
required to be considered. Additionally, frequencies below 10 Hz may also
be excluded in order to avoid the effect of baseline shift (DC
component). Therefore, a considering the aforementioned factors a simple
ratio between the sums of magnitudes of bins of higher frequency (above
about 400 Hz in the first embodiment and above about 500 Hz in the second
embodiment) to those of lower frequency (about 10 Hz to about 400 Hz in
the first embodiment and about 0 Hz to about 500 Hz in the second
embodiment) distinguished the inspiration phase from the expiration phase
of breathing. However, as the preceding embodiments are for exemplary
purposes only and should not be considered limiting, other frequency
ranges may be utilized. Additionally, the method may be fine tuned and/or
modified as desired according to the location and type of the microphone.

[0131] As shown by way of the exemplary embodiments disclosed herein
expiration may have a lower BR value than inspiration. Therefore the
ratio of BRi/BRe for each breathing cycle was calculated in order to
determine the intra-breath relationship between BRi and BRe. BRi/BRe was
surprisingly found to be significantly greater than one. In other words,
for each individual breath BRi is significantly higher than BRe. Since
this exemplary method employs relative changes in spectral
characteristics, it is not believed to susceptible to variations in
overall signal amplitude that result from inter-individual variations.

[0132] The sensitivity of the exemplary method in certain embodiments is
about 90% and 72% for 1.5-fold and 2-fold difference between the two
phases respectively. However, there may be a trade-off between
sensitivity and robustness; choosing a higher frequency cut-off may make
the method more specific and less susceptible to noise but sensitivity
may decrease.

[0133] As disclosed herein, a method for monitoring breathing by examining
BR variables of short segments of breathing acoustic data is provided.
The data was divided into 200 ms segments with subsequent Welch's method
applied on each segment. However, longer or shorter segments may be
desirable in various applications. The method involves applying FFT's on
each segment and averaging the resultant arrays. Averaging FFT results
within the segment further provides a random-noise-cancelling effect. The
method of utilizing BRi/BRe in order to determine the breathing phase
sound data a showed correlation with thoracoabdominal movement as seen in
FIGS. 10a and 10b. Therefore, the currently provided method may be useful
for monitoring, identifying and determining the breathing cycle phases of
an individual. The method may, for example, be utilized for monitoring,
identifying and determining the breathing phase from a pre-recorded audio
track, or the method may also be utilized, for example for real-time
monitoring of breathing.

[0134] For example, in a real-time breathing monitoring situations, BR
variables may be examined in sequence and each BR variable is compared
with a predetermined number of preceding BR values or preceding BR
values. The preceding BR variables may be subject to a moving averaging
window with the length of a breathing phase, which is approximately, for
example 1.4 seconds. However, a longer or shorter window may be utilized
as required. Although in one exemplary embodiment, there is shown a 10-15
fold difference in the BR between the breathing phases, a lower threshold
may be considered. For example, since the moving averaging window
incorporates transitional BR points between the inspiration and
expiration phases which dilute the BR average of a pure breathing phase a
greater or less fold-difference than that noted herein in the exemplary
embodiments may be observed. Accordingly, an empirical threshold of 2 was
chosen for the testing and illustration purposes of an example of the
present method. Utilizing the method as provided herein, about 97.4% of
the breathing phases were classified correctly. It will be appreciated
that while a moving averaging technique is proposed above, other
techniques may be applied to distinguish BR variables that have higher
values (inspiration) from those that have lower ones (expiration).
Exemplary techniques may include, but are not limited to k-means
clustering, fuzzy c-means, Otsu clustering, simple thresholds, etc.

[0135] The method and apparatus as defined herein may be useful for
determining the breathing phases in sleeping individuals as well as being
useful for determining the breathing phases of awake individuals. It
provides a numerical method for distinguishing each phase by a comparison
of segments of the frequency spectrum. The present exemplary method may,
if desired, be used for both real-time and offline (recorded)
applications. In both cases (online and offline) phase monitoring may be
accomplished by tracking fluctuations of BR variables.

[0136] The present exemplary method may be applied to other applications
which require close monitoring of respiration such as in intensive care
medicine, anesthesia, patients with trauma or severe infection, and
patients undergoing sedation for various medical procedures. The present
exemplary method and apparatus provides the ability of integrating at
least one transducer, such as a microphone, and a transducing link with a
medical mask, for example as shown in FIGS. 2a and 2b, and 11 to 22,
thereby eliminating the need to attach a standalone transducer on the
patients' body to monitor respiration. The present exemplary method may
also be used for accurate online breathing rate monitoring and for
phase-oriented inhaled drug delivery, for classification of breathing
phases during abnormal types of breathing such as snoring, obstructive
sleep apnoea, and postapnoeic hyperventilation.

[0137] Thus, the present method may thus be useful to classify breathing
phases using acoustic data gathered from in front of the mouth and
nostrils distal to the air outlets of an individual. A numerical method
for distinguishing each phase by simple comparison of the frequency
spectrum is provided. Furthermore, a method which employs relative
changes in spectral characteristics, and thus it is not susceptible to
variations in overall signal amplitude that result from inter-individual
variations is provided and may be applied in real-time and recorded
applications and breathing phase analysis.

[0174] While the present disclosure describes various exemplary
embodiments, the disclosure is not so limited. To the contrary, the
disclosure is intended to cover various modifications and equivalent
arrangements included within the spirit and scope of the appended claims.
The scope of the following claims is to be accorded the broadest
interpretation so as to encompass all such modifications and equivalent
structures and functions.